There are many occasions in today's industrial world where granular or particulate material contains some specific materials which must be separated from the general mass of granules or particles. For example, ores, scrap material of mixed components, etc. have some valuable components and some waste material. It is, of course, important to recover the valuable components. One method of treating such materials to effect a separation is by electrostatic means, wherein the mixed particles are passed into or near an electrostatic field which attracts some types of materials while not affecting other types. By appropriate placement of the field and of collectors to catch particles falling by gravity, a separation can be made between particles more or less affected by the electrostatic field. A typical apparatus for accomplishing such a separation is described in U.S. Pat. No. 3,998,727 to Gifford. In order for such separation procedures to function efficiently there is a need for sophisticated feeding devices which can transform a mass of particles into a thin moving sheet of particles which can be passed into an electrostatic field which has access to each particle. One such feeding apparatus is described in U.S. Pat. No. 4,421,148 to Knoll and Jackson.
It is an object of this invention to provide an improved apparatus for feeding particles to an electrostatic separation device. It is another object of this invention to provide a novel apparatus for transforming a solid mass of particles into a thin moving sheet of particles travelling at a selected speed and positioned to be fed to the surface of a rotating drum. Other objects will become apparent from the more detailed description which follows.